Ultrasonic control of neurite outgrowth direction

This study investigated a method to control neurite outgrowth direction using ultrasound vibration. An ultrasound cell culture dish comprising a glass-bottom culture surface and a glass disc with an ultrasound transducer was fabricated, and undifferentiated neuron-like PC12 cells were grown on the dish as an adherent culture. The 78 kHz resonant concentric flexural vibration mode of the dish was used to quantitatively evaluate the neurite outgrowth direction and length. Time-lapse imaging of cells was performed for 72 h under ultrasound excitation. Unsonicated neurites grew in random directions, whereas neurite outgrowth was circumferentially oriented during ultrasonication in a power-dependent manner. The neurite orientation correlated with the spatial gradient of the ultrasound vibration, implying that neurites tend to grow in directions along which the vibrational amplitude does not change. Ultrasonication with 30 Vpp for 72 h increased the neurite length by 99.7% compared with that observed in unsonicated cells.

Growth and survival performance of the West African mangrove oyster, Crassostrea tulipa cultivated by suspension and bottom culture methods in the Densu Estuary, Ghana

This study compares the efficacy of suspension and bottom culture methods of the West African mangrove oyster, Crassostrea tulipa, on recycled oyster shell cultches in connection with some environmental factors in the Densu Estuary, Ghana, from December 2017 to July 2018. Oyster spat grew up to 5.56 ± 0.10 cm SH for suspension and 4.60 ± 0.14 cm SH for bottom culture on the convex surfaces of oyster shell cultches, whereas oysters cultured on the concave surfaces by suspension and bottom cultured measured 5.59 ± 0.14 cm SH and 4.68 ± 0.14 cm SH, respectively. There was a significant difference (F = 36.26, p = 0.001) between the growth rate of oysters cultured on convex surfaces of cultches by suspension (0.80 ± 0.23 cm/month) and bottom culture (1.02 ± 0.24 cm/month). The growth rate of cultured oysters on concave surfaces of cultches by suspension (1.00 ± 0.24 cm/month) was significantly better (F = 22.32, p < 0.001) than the bottom approach (0.81 ± 0.23 cm/month). Before the extermination of oysters cultured on the bottom in July 2018, there was no significant difference in the survival of oysters cultured by suspension and bottom methods on the convex (χ2 = 0.06, p = 0.99) and concave surfaces (χ2 = 0.19, p = 0.99). Of the physico-chemical factors monitored, oyster growth and survival were significantly influenced by DO (p = 0.004; 0.039) and salinity (p = 0.027; 0.012), respectively. Suspension culture approach should be preferred over the bottom culture, especially for water bodies with low bulk density.

The trials of seaweed Caulerpa racemosa cultivation using the off-bottom culture at The Kastela Waters, Ternate Island Districht, Ternate City

Seaweed of Caulerpa racemosa has bright prospects for cultivation. In North Maluku province in general, the cultivation of seaweed Caulerpa sp has never been developed, even though the waters of North Maluku have enormous potential, because this type of seaweed is scattered in various marine waters in North Maluku. One of the efforts that needs to be done is to carry out this type of seaweed cultivation in an optimal and sustainable manner.The seaweed Caulerpa racemosa cultivation unit used in this study was the off-bottom method measuring 5 m x 10 m. This size can contain 5 stretch ropes/risers with a length of 10 m and a distance of 1 m between the stretch ropes/risers. Each stretch / riser line contains about 45 seed clump points with a distance between clumps of 15 cm. The observation procedure for the growth of Caulerpa racemosa seaweed was carried out by weighing the seaweed seeds in each stretch/riser rope. The weight of seed that is weighed is the weight of seeds at the time of planting and the weight of seaweed at harvest.The results showed that the average growth rate of seaweed Caulerpa racemosa was varied for each rope. In ris 1 rope, the average absolute weight growth reached 100.88 grams, ropes 113.33 grams, ris rope 3, 88.00 grams, rope ris 4, 116.00 grams, and rope ris 5, amounting to 113, 33 grams. In general, the highest growth in absolute weight was found in the fourth rope, which was 116.00 grams.

Small invertebrates in bivalve-cultivated and unmodified habitats of nearshore ecosystems

Many nearshore ecosystems are modified by aquaculture, including bivalve culture to produce food and restore extirpated populations. Small invertebrates in nearshore ecosystems support fundamental ecological processes, but the effects of bivalve culture on invertebrates are incompletely understood. Here, we compared invertebrate assemblages from multiple studies of bivalve-cultivated and unmodified nearshore habitats along the US west coast. In general, unmodified eelgrass and nearby off-bottom culture habitats with eelgrass present were inhabited by a greater abundance, richness, and diversity of epibenthic invertebrates than bottom culture and bare (mud, sand) habitats that both lacked eelgrass. Findings of individual studies suggested: minor differences in epibenthic invertebrate assemblages associated with various aquaculture practices; restoring native oysters to mudflats did not detectably alter epibenthic invertebrate abundances; epibenthic invertebrates were more abundant on shell hash introduced to mudflats than unmodified mudflats; and benthic invertebrates were less abundant, rich, and diverse in habitats cultured on bottom by Manila clams. Considering the range of these patterns, there appears to be potential for coastal communities to restore extirpated bivalve populations or develop bivalve culture practices that meet objectives to grow food while maintaining nearshore ecosystems’ fundamental processes supported by robust invertebrate assemblages.

On the edge: assessing fish habitat use across the boundary between Pacific oyster aquaculture and eelgrass in Willapa Bay, Washington, USA

Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which involve extensive use of estuarine tidelands. Pacific oyster Crassostrea gigas aquaculture is a century-old practice in US West Coast estuaries that contributes significantly to the regional culture and economy. Native eelgrass Zostera marina also commonly occurs in intertidal areas where oyster aquaculture is practiced. Eelgrass is federally protected in the USA as ‘essential fish habitat’, restricting aquaculture activities within or near eelgrass. To contribute scientific information useful for management decisions, we sought to compare fish habitat use of oyster aquaculture and eelgrass, as well as the edges between these 2 habitats, in Willapa Bay, Washington, USA. Furthermore, given a recent shift towards off-bottom culture methods, in part to protect seagrasses, long-line and on-bottom oyster aquaculture habitats were compared. A combination of direct (underwater video, minnow traps) and indirect (predation tethering units, eelgrass surveys) methods were employed to characterize differences in fish habitat use. Eelgrass density declined within both aquaculture habitats but less so within long-line aquaculture. Most fish species in our study used long-line oyster aquaculture and eelgrass habitats similarly with minimal edge effects, and on-bottom aquaculture was used less than either of the other 2 habitat types. These results are consistent with previously observed positive relationships between fish abundance and vertical habitat structure, but also reveal species-specific behavior; larger mesopredators like Pacific staghorn sculpins were sighted more often in aquaculture than in interior eelgrass habitats.

Seed production and culture of abalone in Vietnam.

This paper presents the techniques of seed production and culture of abalone (Haliotis asinina) using three methods: cage culture in concrete tanks, cage culture in the sea and bottom culture on a rocky beach. These are the results of a study carried out for many years by the Ministry of Fisheries of Vietnam. Based on the results obtained, commercial seed production and transfer techniques of seed production of abalone in four provinces, Khanh Hoa, Ninh Thuan, Phu Yen and Quang Nam, are being carried out.